Research On Key Component—equalizing Beam Remanufacturing In Engineering Machinery

Due to the current resources, increasingly nervous energy, increasing pressure, it is the time to develop the engineering machinery remanufacturing industry, which can effectively reduce the energy consumption resources and waste emissions, and change the traditional linear growth mode of mining smelting- manufacturing- waste, into a circular economy mode of resources- products- waste- renewable resources. The development of engineering machinery remanufacturing industry is also an embodiment of green manufacturing in the document of the national medium and long-term science and technology development plan outline(2006-2020).Many of the engineering machinery, such as Caterpillar has been carried out in the engine remanufacturing business, but their core technology is under repairing and changing. Under the financial support of major technical innovation project of retired engineering machinery products and remanufacturing reverse logistics technology research and application by XCMG Group, this paper investigated the hardfacing technology applied in the engineering key parts remanufacturing process.By analyzing the failure mode, size detection and microscopic surface observation of the equalizing beam, it can be found that the failure model of the equalizing beam is mainly of the circular furrow and microporous. It is suitable to remanufacture the equalizing beam by using the hardfacing technology when the wall thickness ratio of equalizing beam is controlled in 0.85~ 1.20(wall thickness difference < 3 mm).The microstructure and the performance test were carried out to make sure that the performance of remanufactured equalizing beam is beyond the new one. The results indicate the microstructure of the equalizing beam is consisted of ferrite and pearlite, and the average microhardness and tensile strength of the equalizing beam is 196.36 HV and470.46 MPa, respectively. The thickness of the fatigue layer is 0.5~ 1.5 mm, which is determined by the cross-section microhardness measurement. Through the cross-section microhardness measurement to determine the equalizing beam fatigue layer thickness is0.5 ~ 1.5 mm.On this basis, the CALPHAD software was applied for the development of the flux cored wire of the YD-607 Q for hardfacing the inter hole of the equalizing beam. Moreover,the hardfacing parameters and was optimized and the microstructure and the performance of the hardfacing specimens were measured. The results indicate that the microstructure of the remanufactured layer is consisted of ferrite and pearlite.A good metallurgical combination of hardfacing metal and the matrix can be observed and no defects such as inclusions or porosity can be seen in the combination interface. The microhardness of the hardfacing layer is 270 HV~ 290 HV, and that of the HAZ is 180~270 HV, which can be satisfied for the drawings and performance requirements. The mass loss of the hardfacing layer is 0.229 g/h, and that of the equalizing beam matrix is 0.303 g/h under the same wear test parameters. The wear-resistance of the remanufacturing layer is better and can be used for equalizing beam remanufacturing.