Analysis and Discrimination of the Causes of Crankshaft Ablation

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Analysis and Discrimination of the Causes of Crankshaft Ablation

Source: China Bearing Network Time: 2017-11-05

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Crankshaft ablation; mainly due to the failure of the crankshaft journal and the bearing bush to form a useful smooth oil film; the crankshaft journal directly conflicts with the bearing bush. When the diesel engine attacks the crankshaft ablation; it will emit white smoke; announce metal impact abnormal sound Sound; even the crankshaft and the bearing bush are locked together and cannot be changed. Therefore, it is necessary to correctly analyze and discriminate the cause of the attack.
1The quality of the oil is poor 1) The quality of the oil is low. The quality grade and viscosity grade of the selected oil are lower; or the different trademark oils are used for blending; the performance of the oil is not up to the demand, and a lot of dust is mixed in the oil application process. And because the working temperature of the diesel engine is too high, the oil is oxidized and transformed. The oil of the oxidized cerium is black and dull; the concentration is increased; the oil is rubbed with two fingers; the oil is found to have dust, impurities, etc. If the oil used is found to have the above appearance It is necessary to replace it in time.
2) The oil is thinned. Because some diesel engine fuel injection pumps are smooth and smooth, the pressure is smooth; once the fuel injection pump and the smooth oil passage seal are ineffective, the diesel oil enters the smooth oil chamber; the diesel engine will be diluted with the smooth oil. In addition, if the water jacket has cracks or Bottom hole; making cooling water into the oil will also make the oil thin.
You can check whether the upper part of the diesel engine (plane on the cylinder head, valve structure, cylinder head cover) can have water vapor or water droplets. If it is found that the oil capacity is added in the application, the concentration is decreased; the viscosity is decreased; and the oil smell is clarified. Diesel oil is mixed in the oil.
2 The oil inventory is not good, the oil pressure is low, the oil inventory is not good, and the oil pressure is low; it will constitute a lack of smooth oil flow of the diesel engine; thus, it can not ensure a smooth oil film between the crankshaft journal and the bearing bush of the diesel engine.
You can check the amount of oil in the oil sump and the reading of the oil pressure gauge; further check the oil pipeline for abnormalities such as clogging and leakage.
3 The crankshaft journal and the bearing bush are too large or too small. 1) The crankshaft journal and the bearing bush are too large; the diesel engine oil pressure is low; it cannot be configured to satisfy the smooth oil film.
2) The crankshaft journal and the bearing bush are too close.
When the gap is too large or too small; the cylinder, bearing hole, bearing bush scale can be viewed with a micrometer and a cylinder table; the cooperation gap can be calculated; and the cooperative gap can also be directly measured by the feeler gauge.
4 crankshaft or cylinder size deviation 1) crankshaft radial runout error is large; make the journal and bearing bush gap is small or no gap; smooth oil film thickness is not good or no smooth oil film.
2) The coaxiality of the main bearing bore of the cylinder is too poor; the gap between the main journal and the bearing shell is too small or void; the thickness of the smooth oil film is not good or there is no smooth oil film.
3) The straightness of the cylinder and the main bearing hole is too poor; the gap between the journal pin and the main journal is too small or void; the thickness of the smooth oil film is not good or there is no smooth oil film.
In the case that the diesel engine is not used for a long time after the new machine or overhaul; it will often constitute the above-mentioned appearance. It is concluded that several scales of the excess position can be shaken by hand to crank the diesel engine crankshaft (rotational force); then the diesel engine mains are unloaded by cylinder. Bearing cap and connecting rod bearing cap; re-transform the crankshaft. According to its rotating crankshaft torque, 浠钜 浠钜 淳咛 淳咛 范 ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
5 crankshaft main journal, connecting rod journal shape dimension is out of the crankshaft main journal, connecting rod journal or cylinder main bearing hole, connecting rod big hole cylindricity or taper difference; both will make the journal and bearing bush gap intermittent (continuous) or tapered. It is not guaranteed to form a good smooth oil film.
After the new machine or overhaul, the diesel engine is not put into operation for a long time; it is easy to attack the above-mentioned appearance; the journal scale can be measured. If the journal is ablated, the adjacent journal can be measured (the adjacent corresponding journal is used according to the convention) Use the same equipment, the same cutting tool processing; then it can represent the shape error of the ablation journal).
6 The crankshaft main journal and the connecting rod journal have poor surface roughness due to poor roughness; there are many metal peaks on the outer surface of the journal; it destroys the integrity and continuity of the smooth oil film between the journal and the bearing bush. The peak directly conflicts with the bearing bush; it constitutes crankshaft ablation.
Frequent attacks occur after the new machine or overhaul. The diesel engine is not put into operation for a long time. If the measured journal is ablated, the roughness detector can be used to measure the adjacent corresponding journal (since the case is; the adjacent equipment is selected by the same equipment, The same cutting tool is processed; then the measured roughness can represent its ablation journal roughness).
7 crankshaft, flywheel, clutch dynamic balance, ultra-difference dynamic balance, super-difference; crankshaft high-speed rotation, inertial force; the crankshaft journal and bearing bush cooperation gap will be damaged; severely, the journal and the bearing bush directly collide to form crankshaft ablation .
The problem usually occurs when the machine travels for 10,000km. After the crankshaft is ablated, the residual debris on the journal can be removed; the balance is checked from the head; the unbalance can basically indicate the ablation of the axicon.
8 Protection and protection If the diesel engine is not operated for a period of time, if it is not properly protected and protected in time, the components such as the oil pump pressure limiting valve will be worn and deformed. The oil filter element will be blocked by oil and sludge; Falling; causing crankshaft ablation.
Crankshaft ablation; mainly due to the failure of the crankshaft journal and the bearing bush to form a useful smooth oil film; the crankshaft journal directly conflicts with the bearing bush. When the diesel engine attacks the crankshaft ablation; it will emit white smoke; announce metal impact abnormal sound Sound; even the crankshaft and the bearing bush are locked together and cannot be changed. Therefore, it is necessary to correctly analyze and discriminate the cause of the attack.
1The quality of the oil is poor 1) The quality of the oil is low. The quality grade and viscosity grade of the selected oil are lower; or the different trademark oils are used for blending; the performance of the oil is not up to the demand, and a lot of dust is mixed in the oil application process. And because the working temperature of the diesel engine is too high, the oil is oxidized and transformed. The oil of the oxidized cerium is black and dull; the concentration is increased; the oil is rubbed with two fingers; the oil is found to have dust, impurities, etc. If the oil used is found to have the above appearance It is necessary to replace it in time.
2) The oil is thinned. Because some diesel engine fuel injection pumps are smooth and smooth, the pressure is smooth; once the fuel injection pump and the smooth oil passage seal are ineffective, the diesel oil enters the smooth oil chamber; the diesel engine will be diluted with the smooth oil. In addition, if the water jacket has cracks or Bottom hole; making cooling water into the oil will also make the oil thin.
You can check whether the upper part of the diesel engine (plane on the cylinder head, valve structure, cylinder head cover) can have water vapor or water droplets. If it is found that the oil capacity is added in the application, the concentration is decreased; the viscosity is decreased; and the oil smell is clarified. Diesel oil is mixed in the oil.
2 The oil inventory is not good, the oil pressure is low, the oil inventory is not good, and the oil pressure is low; it will constitute a lack of smooth oil flow of the diesel engine; thus, it can not ensure a smooth oil film between the crankshaft journal and the bearing bush of the diesel engine.
You can check the amount of oil in the oil sump and the reading of the oil pressure gauge; further check the oil pipeline for abnormalities such as clogging and leakage.
3 The crankshaft journal and the bearing bush are too large or too small. 1) The crankshaft journal and the bearing bush are too large; the diesel engine oil pressure is low; it cannot be configured to satisfy the smooth oil film.
2) The crankshaft journal and the bearing bush are too close.
When the gap is too large or too small; the cylinder, bearing hole, bearing bush scale can be viewed with a micrometer and a cylinder table; the cooperation gap can be calculated; and the cooperative gap can also be directly measured by the feeler gauge.
4 crankshaft or cylinder size deviation 1) crankshaft radial runout error is large; make the journal and bearing bush gap is small or no gap; smooth oil film thickness is not good or no smooth oil film.
2) The coaxiality of the main bearing bore of the cylinder is too poor; the gap between the main journal and the bearing shell is too small or void; the thickness of the smooth oil film is not good or there is no smooth oil film.
3) The straightness of the cylinder and the main bearing hole is too poor; the gap between the journal pin and the main journal is too small or void; the thickness of the smooth oil film is not good or there is no smooth oil film.
In the case that the diesel engine is not used for a long time after the new machine or overhaul; it will often constitute the above-mentioned appearance. It is concluded that several scales of the excess position can be shaken by hand to crank the diesel engine crankshaft (rotational force); then the diesel engine mains are unloaded by cylinder. Bearing cap and connecting rod bearing cap; re-transform the crankshaft. According to its rotating crankshaft torque, 浠钜 浠钜 淳咛 淳咛 范 ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
5 crankshaft main journal, connecting rod journal shape dimension is out of the crankshaft main journal, connecting rod journal or cylinder main bearing hole, connecting rod big hole cylindricity or taper difference; both will make the journal and bearing bush gap intermittent (continuous) or tapered. It is not guaranteed to form a good smooth oil film.
After the new machine or overhaul, the diesel engine is not put into operation for a long time; it is easy to attack the above-mentioned appearance; the journal scale can be measured. If the journal is ablated, the adjacent journal can be measured (the adjacent corresponding journal is used according to the convention) Use the same equipment, the same cutting tool processing; then it can represent the shape error of the ablation journal).
6 The crankshaft main journal and the connecting rod journal have poor surface roughness due to poor roughness; there are many metal peaks on the outer surface of the journal; it destroys the integrity and continuity of the smooth oil film between the journal and the bearing bush. The peak directly conflicts with the bearing bush; it constitutes crankshaft ablation.
Frequent attacks occur after the new machine or overhaul. The diesel engine is not put into operation for a long time. If the measured journal is ablated, the roughness detector can be used to measure the adjacent corresponding journal (since the case is; the adjacent equipment is selected by the same equipment, The same cutting tool is processed; then the measured roughness can represent its ablation journal roughness).
7 crankshaft, flywheel, clutch dynamic balance, ultra-difference dynamic balance, super-difference; crankshaft high-speed rotation, inertial force; the crankshaft journal and bearing bush cooperation gap will be damaged; severely, the journal and the bearing bush directly collide to form crankshaft ablation .
The problem usually occurs when the machine travels for 10,000km. After the crankshaft is ablated, the residual debris on the journal can be removed; the balance is checked from the head; the unbalance can basically indicate the ablation of the axicon.
8 Protection and protection If the diesel engine is not operated for a period of time, if it is not properly protected and protected in time, the components such as the oil pump pressure limiting valve will be worn and deformed. The oil filter element will be blocked by oil and sludge; Falling; causing crankshaft ablation.

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