What material is the crankshaft on the engine made of? Can it be repaired if it is damaged?
Do you know what is the most expensive and precise single component on the car engine? Many people may not imagine that it is the engine crankshaft. It is a very important part on the engine, it can convert the linear motion of the piston into rotary motion, and transform the gas pressure from the piston and connecting rod into torque outward, and drive the transmission system of the car as well as the engine's gas distribution mechanism and other auxiliary devices.
The force on the crankshaft is extremely complex. It works under the combined action of the periodically changing gas pressure, reciprocating inertia forces and their moments, and is subjected to huge bending and torsional alternating loads. At the same time it is also a slender high-speed rotating part, so it needs strict dynamic balance, bending and twisting are not allowed to exceed a certain value.
Therefore, the crankshaft needs to be made of very high quality materials and undergo a rigorous surface treatment process. After forging or casting, in order to improve the fatigue strength of the crankshaft and eliminate stress concentration, the surface of the journal needs to be shot blasted and the rounded corners need to be rolled; in order to improve the surface hardness of the journal, the surface of the journal also needs to be high frequency quenching or nitriding treatment, and finally finishing. After this treatment, the crankshaft has sufficient fatigue strength and stiffness against bending and torsion, while the journal has a large enough pressure-bearing surface and wear resistance.
In the crankshaft there are oil channels through the main journal, crank and connecting rod journals, the pressure oil from the main oil channel of the lubrication system into the main journal and connecting rod journals, in order to lubricate the main journal and main shaft tile, connecting rod journal and connecting rod shaft tile these two friction pairs. But because these two parts are subjected to huge forces, so there is bound to be a certain degree of wear in use; if poor lubrication or excessive engine load, there will be other types of damage.
But in the actual engine repair process, the crankshaft is generally rarely repaired, there are defects directly replaced. On the one hand, because the crankshaft repair is more difficult, the process is more complex, requires high precision, the cost is also more expensive, both economically and technically, are not cost-effective; on the other hand, the vast majority of models are not provided with increased size repair shaft tile, crankshaft repair grinding can not be found with the accessories; there is a very important point is that now has the ability to repair the crankshaft of the enterprise There are less and less, many provinces only the provincial capital cities have such processing enterprises, repair a crankshaft also have to travel a long way back and forth several times, is not worth. Therefore, now only some extremely special engines, it is difficult to buy parts, or buy a very long period, such crankshaft to repair at any cost, more directly scrapped.
