The actual oil film pressure in the bearing includes not only the oil wedge pressure generated by the constant speed load, but also the squeezing force generated by the circumferential and radial displacement during the rotation of the crankshaft. Therefore, when the speed is constant, the position of the crankshaft’s axis and The oil film pressure is a function of the crankshaft angle, forming a pulse load, and the bearing and the bearing seat simultaneously undergo bending deformation and even arouse bending vibration.
The main reason for shingling is 16v28. Diesel engine shingling is related to the overhaul, assembly and manufacturing quality of diesel engine block, crankshaft and bearing bush. It is also related to the driver’s operation, maintenance and lubrication conditions in actual use. According to 16V28 in recent years.
From the analysis of the current situation of the rolling of the diesel engine, there are several main reasons for the occurrence of the rolling: (1) The coaxiality of the main bearing hole is out of tolerance. Due to the excessively poor coaxiality of the main bearing hole, local contact between the journal and the bearing bush is caused, so that the load is concentrated on one side of the bearing bush and causes the bush to be crushed.
On DF. No. 7 locomotive, due to the out-of-tolerance of the main bearing hole, the fifth main bearing was severely shattered three times. After disassembly and measurement of the crankshaft runout, it was found that the runout was out of tolerance. Although it met the requirements for overhauling, it exceeded Requirements for new cars. Through the analysis of the coaxiality data of the body, the fifth main bearing of the diesel engine has the largest coaxiality, and the bearing may be carried by the fifth main bearing of the dry body, plus the fifth main bearing has the largest coaxiality. , The fifth position of the crankshaft has a large runout, which causes the main bearing to carry more than the oil wedge capacity, causing dry friction, and then rolling. DFI: No. 252 diesel engine of 075 locomotive was found to have out-of-tolerance in the assembly of the engine body. The approval procedures were completed. Although there was no shingling during the factory, it did not arrive 3 months after the factory was put into operation. The diesel engine ranked fifth The main bearing bush was shattered, and it was returned to the factory for repair.
(2) The oil pressure is too low. Long-term traction under the condition of low oil pressure of the locomotive will inevitably cause the diesel engine to rub the bushes. DFS. Due to the low oil pressure, the l-cylinder connecting rod bush, the 9-cylinder connecting rod bush edge and the crankshaft connecting rod neck between the I and 9 cylinders will be rubbed. After the crankshaft’s top connecting rod neck was properly polished, its dimensions were measured, and it was found that the front half of the connecting rod neck was severely out of tolerance, and the rear half was slightly worn. The piston head was caused by excessive wear of the connecting rod bearing of the l-cylinder. Touching the bottom plane of the clamp of the cylinder head will cause knocking sound, and the connecting rod bearing and crankshaft will be locked and rotated, which will cause severe wear of the crankshaft.
(3) The cleanliness of the oil system of the vehicle is poor. Fll locomotive lubricating oil system involves a wide range and requires strict control of each process. In recent years, DFI has occurred. The three locomotives 01146, 0145, and 014 have not been cleaned due to impurities during assembly of the coarse filter, such as materials flashing into people. The main oil passage of the diesel engine caused the connecting rod bearing and main bearing bearing to be strained.
(4) The quality of the bearing itself. The main reason is that the thickness of the alloy layer of the bearing bush is too large or the thickness is uneven, so that the surface of the alloy is partially exposed to the steel, and the alloy and the steel back are not well bonded. It often happens on DF; type locomotives. Due to the poor bonding force between the bearing steel back and the alloy layer of the No. 2495 diesel engine, the diesel engine test station drove to 17-19 working conditions and stopped for dismantling. It was found that the third main bearing bearing was crushed.
(5) In the cold winter, the locomotive heating work did not strictly implement the technical requirements, and did not preheat the diesel engine to the specified oil and water temperature. When the oil temperature is low, the oil will have high viscosity, poor fluidity and slippery. The oil does not reach every frictional part, causing the individual parts to be short of oil instantaneously. As soon as the diesel engine rotates, the individual parts are rubbed dry.
The rapid heating generated heat, which resulted in shingling of the bushings, which eventually expanded to the entire bearing shinglings. Over time, it was worn to the back of the steel, and the No. 250 diesel engine of the locomotive produced the fifth-gear main bushings.
(1) When a very small amount of alloy fragments are found on the oil sump oil network, it may be caused by the connecting rod bushing strain or bushing. At this time, observe and analyze the corresponding parts of the cylinder head and remove the connecting rod bush. If it is a minor strain, use oilstone to grind the connecting rod bearing. If the strain is serious, replace the connecting rod bearing and rub the strained surface of the crankshaft journal with a whetstone, and then go to the diesel engine test station for testing. (2) When there are a large number of alloy fragments on the oil sump oil net, it is judged to be caused by the main bearing bushing. At this time, the diesel engine needs to be lifted and returned to the assembly station for disassembly, and the data is re-measured, the tiles are re-allocated, and the regulations are strictly followed. operate. (3) According to the current situation of the poor bonding force between the bearing alloy and the steel back, the corresponding detection methods are adopted, such as ultrasonic thickness measurement and ultrasonic flaw detection; try to do the bonding force test of the alloy and the steel back in the central laboratory to make it meet the specified requirements, and Carry out irregular inspections.
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