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