EQUIPMENT AND TECHNOLOGY FOR RESTORATION HEAVY LOADED DIESEL CRANKSHAFTS LOCOMOTIVES AND SHIPS
A package of technologies is proposed that can be implemented on the basis of the USM-5 installation and powder wire PP-2(TOPAS)
APPOINTMENT. Are intended for drawing dense wear-resistant coverings on working surfaces of units and details:
1. In ship repair during the restoration of ship crankshafts and other parts of marine engines, parts of the auxiliary machinery of the engine room. The coating can be used to restore and improve the reliability of the friction pair parts of most units, such as shafts in stern pipes, friction parts of sediments, and the like.
2 In locomotive and wagon depots during the restoration of diesel locomotive crankshafts, restoration of the necks of friction elements of other locomotive parts, when restoring seats under bearings on the axle of wheel pairs.
3. In large car parks, when crankshafts are restored and other car parts
NOVELTY: A new technology for coating the working surfaces of the crankshafts is based on the newly developed combined electric arc metallization method in a supersonic high-temperature jet of combustion products of air and natural gas.
Improving the quality of coatings to a level that provides a sufficient margin of operational reliability is achieved through two innovations: - use as an atomizing gas of an economical supersonic flow of hot combustion products of methane with air at the USM-5 unit; - use for the spraying of the special powder wire PP-2(TOPAS).
In this case, in comparison with conventional processes, the kinetic energy of the sputtered particles rises 4 to 5 times, their flight speed increases from 70-150 m / s to 250-300 m / s. Reducing the time of contact of molten droplets with the atmosphere during the flight to the base plus a reduced concentration of oxygen in the surrounding stream of combustion products ensures more complete preservation of carbon and alloying elements in the coating.
- in comparison with the typical process of electric arc spraying, the degree of carbon burning falls from 40-60% to 3-6%, and silicon and manganese from 20-25% to 2-3%.
- The technology makes it possible to obtain composite coatings from a flux-cored wire with a sufficiently large (twofold) safety factor - the adhesion strength of the coating with the substrate increases from 20-40 MPa to 55-80 MPa, the porosity decreases from 8-15% to 0-2 %
- a distinctive feature of such coatings is a homogeneous lamellar structure, low (~ 1.5%) porosity, which prevents shrinkage of the coating during the operation of parts, even distribution of free graphite.
Thanks to this, the coating can withstand the long high cyclic loads and overloads that occur during the operation of powerful diesel engines
Due to the residual (up to 2%) porosity, the coating is evenly distributed throughout the volume of the reconstituted layer and retains the oil, especially required when starting a cold engine. Free graphite comes to the surface during operation and fulfills the role of an additional solid lubricant.
For this reason, remarkable is the fact that in extreme and emergency situations (stopping the supply of oil, the presence of abrasive particles), the coating shows a large vitality in compared to the main material crankshaft