Mechanism And Experimental Study On Carbonaceous Deposits Removal Of Turbine Shaft By Magnetic Abrasive Finishing Technology

Turbine shaft is an important part of aero-engine.The carbonaceous deposits formed on the surface of turbine shaft after fuel combustion.It needs to be cleared to ensure the normal operation of the engine.At present,to adopt hot alkali process to removal carbonaceous deposits have some problems such as long time consuming,poor removal effect,serious environmental pollution and so on.As a new ultra-precision surface finishing technology,magnetic abrasive finishing can be used to remove carbonaceous deposits.But there is a lack of corresponding theoretical and technological research.This paper starts with the analysis of carbonaceous deposits composition,designs and analyzes the magnetic circuit,and carries out the experiment of removing carbonaceous deposits on the surface of turbine shaft by magnetic abrasive finishing.The main research contents and conclusions are as follows:(1)By observing the micro-morphology and analyzing the composition of carbonaceous deposits,it is concluded that carbonaceous deposits can be divided into massive and spherical.And the main components of massive carbonaceous deposits are carbon and oxygen,while the main components of spherical carbon deposition are iron and carbon,in which the content of carbon is 60.09% and 26.79% respectively.By analyzing the microstructure of carbonaceous deposits,it is determined that the main structure is graphite crystal,which provides theoretical support for carbonaceous deposits removal.(2)By analyzing the finishing mechanism of magnetic abrasive finishing to remove carbonaceous deposits on the inner surface of turbine shaft.It is concluded that the main influencing factors of magnetic abrasive effect on carbonaceous deposits on the inner wall of pipe fittings are: magnetic induction intensity of processing area,internal magnetic pole rotating speed and abrasive filling amount.The arrangement of magnetic poles in the magnetic circuit is compared and analyzed,and the axial magnetic pole compound magnetic circuit is selected.Which compared with the single pole arrangement scheme,the average magnetic induction is increased by 50%,which can effectively increase the grinding pressure of magnetic abrasive.(3)Based on the magnetic circuit scheme,a test platform for the removal of carbonaceous deposits from the surface area of turbine shaft by magnetic abrasive finishing is established.The carbonaceous deposits removal test was carried out,and the influence of single factor on the surface roughness of the inner wall of turbine shaft was revealed.The quadratic regression equations of feed speed,grinding particle filling amount and inner pole rotating speed on surface roughness are established,and the optimal combination of process parameters is determined.The experiments of magnetic abrasive finishing and removal of turbine axle carbonaceous deposits were carried out.The results show that the carbon content on the surface of the turbine shaft decreases by 96.9%,and the element types are consistent with the turbine shaft matrix composition.The carbonaceous deposits on the inner surface of the turbine shaft are completely removed.Magnetic abrasive finishing compared with the original carbonaceous deposits removal technology,the surface roughness Ra of the turbine shaft decreases by 65%.Through the research on the removal mechanism and process of carbonaceous deposits on the surface area of turbine shaft by magnetic abrasive finishing,the results show that magnetic abrasive finishing meets the requirements of removing carbonaceous deposits on the surface area of turbine shaft,and the determined process parameters lay the foundation for the design of magnetic abrasive finishing equipment to remove carbonaceous deposits on the surface area of turbine shaft.