Diesel engine spindle bush and connecting rod tile failure classification can be divided into three categories: tile smashing, lava and tile burning.
1 the essence of diesel engine smashing is that the diesel engine bearing alloy is spalling off, so that there is a cavity on the working surface of the bearing bush.
The surface of the alloy after use may not only appear parallel, scaly or reticulate, but also make the alloy spot, block, or flake. The reason is that the gap between the shaft neck and the Bush is too large, the oil is deteriorated or the strength is not enough, and the oil film is disappearing under the impact force between the shaft and the tile, so that the alloy on the tile is produced. When cracking occurs, the alloy shedding off the lump. The RAS is the inner surface of the bearing bush appearing along the circumferential direction of the bearing bush, forming a linear or banded tensile mark.
It is often due to oil dirty, small mechanical impurities mixed in the oil, as the oil flows between the shaft and the tile. The hard impurities often pull the alloy of the tile, and the crankshaft neck can be pulled seriously when it is serious.
Burning tile is a phenomenon between the crankshaft journal and bearing bush, which causes the bearing alloy to be burned due to the lack of oil lubrication.
2 the damage mechanism of the diesel engine is mostly caused by the destruction of the lubricating oil film between the shaft neck and the axle bush, which causes the dry friction between the axle bush and the shaft neck. The bearing of the axle is softened and even melted and bitten on the neck of the shaft because of the heat of friction. The friction between the steel back and the seat hole further causes high temperature. At this time, the bearing bush can be burnt out, or the connecting rod bolt can be broken, and the large end cover of the connecting rod is thrown out to break the cylinder block.
3 diesel engine burning is a comprehensive fault of the axle bush, mainly due to poor lubricating oil and too large gap between axle bush. In addition, because of the leakage of oil, the oil pressure is low and the oil pressure is low; the mechanical impurity or oil pollution is blocked by the oil channel; the oil pump's filter collector is bad, the oil bottom oil is short of oil and so on, all will lead to the burning accident hair. In practice, it has been proved that the untimely treatment of the lava and smash will also lead to the occurrence of the burning accident. This is due to the low oil pressure and the low oil pressure after the lava or the smash. Therefore, the oil pressure and the oil warning lamp during the operation of the diesel engine should be paid attention to in the use of the engine.
In the past, the replacement of axle bush in our country adopted the shaft matching method, that is, according to the wear condition of the crankshaft and axle, it decided to replace the shafts of which size to reduce the size. Then the crankshaft was worn first, the handmade shaving axle or the boring machine was used to boring the bearing bush. But the domestic and imported engineering machinery diesel engines were used in our country at present. For example, it is very unsuitable. This is because the shaft of the new diesel engine is mostly without scraping. In other words, the axle bush is not allowed to be scraped. Therefore, the replacement of the axle bush is exactly the opposite of the past. At this time, the size of the shaft neck should be determined with the hole distribution axis, that is, the size of the curved axis with the size of the hole.
Taking the Cummins 6BT5.9 diesel engine as an example, in the use of the standard axle bush, it is generally not necessary to repair and scrape as long as the clearance is in the prescribed value of the original plant. In addition, the contact area of the working surface of the axle bush should not be doubted. Even if there is no larger contact area at that time, the contact area will be reached only after the running of the running in period. More than 90%. The bearing surface of the new diesel engine is not adjusted with the shim. The original shaft is made of no pad boring. Therefore, after the wear of the axle bush is loose, it is not allowed to add copper or paper to the back of the axle bush. And the gap between the axle Bush and the neck is strictly prohibited. The height of the pedestal. The empirical method to check the gap between the shaft neck and the axle bush is to apply a thin oil to the bearing bush, put a thin oil on the axle bush, put the connecting rod on the corresponding shaft neck, tighten the bolt on the prescribed moment, then rotate the connecting rod with the hand, and turn the 1/2 - 1 circle, and there is no clearance feeling when the axis is drawn to the connecting rod, that is to say it is in accord. For the inspection of the crankshaft main axle bush and the gap between the axle neck, the oil can be coated on the surface of the axle neck and axle bush. The main bearing seat cover of the crankshaft is installed and the bolt is tightened according to the specified torque. Then the crankshaft is wrenched in both hands to rotate the 1/2 ring with the crankshaft, and turn light, even without retardation.
