Process vibration trend The total axis of the unit diagram trajectory diagram before and after the alarm changes the maximum speed below 50 rpm, oil temperature, oil pressure changes are small, no large fluctuations, the temperature of the thrust tile does not change much before the alarm, and from 11.20 days later From 69 ° C to the current 82.7 ° C, the increase rate is 13.7 ° C, the lubricating oil inlet temperature is 43.3 ° C, the oil pressure 0.14MPa no large fluctuations. (2) Monitoring and analysis According to the above actual situation and online monitoring, there are reasons: 1 and the field instrument display card and LCD display error. 2 The variable load of the compressor process condition reduces the flow rate of the gas flowing through the compressor to a certain extent, and the unit generates a rotating stall. After the occurrence, the rotor generates a large axial exciting force, so that the shaft displacement is further increased to reach the alarm; The fluctuation of the inlet and outlet pressures causes a surge phenomenon. On-site process: a section of inlet pressure 0.52MPa, three sections of outlet pressure 5.2MPa, a section of inlet air temperature of 15 ° C, three sections of outlet temperature of 82 ° C, compressor support bearing temperature TI-5623, TI-5624 are 56 ° C, 67 ° C, respectively The thrust bearing temperatures TI5621 and TI5622 are 81°C and 55°C respectively; so far, the thrust bearing temperature TI5621 has risen to “85°Câ€, and the three-stage outlet flow rate fluctuates between 9194T/h. Under the rated working condition, the inlet flow rate of the compressor should be 134.345T/h, and the actual flow rate is 126T/h. This process condition is lower than the design condition before and after the alarm. Measures (1) Open the large compressor return valve to increase the inlet flow of the compressor by means of backflow. (2) Increasing the oil pressure of the lubricating oil inlet and lowering the oil temperature to suppress or eliminate the tendency of the vibration to increase. (3) Change the speed and increase the flow rate (because the actual flow is less than the rated flow). If the above suggestions are not achieved, in order to minimize the loss, the thrust tile should be stopped according to the actual situation. During the inspection, if there is a slight wear scar on the main thrust tile, the shaft and the thrust plate are worn out, and the new thrust tile is replaced and replaced, and the rated process parameters of the compressor are adjusted. After testing, the axial displacement dropped significantly to about 260 μm. Conclusion The variable load of the compressor process conditions makes the compressor surge and rotational stall is the main cause, followed by the surge; after the occurrence, the rotor generates a large axial excitation force, which further increases the shaft displacement to reach the alarm. In order to strengthen the predictive maintenance of key equipment, the state monitoring technology of large rotating machinery is used to continuously monitor the large-scale units around the clock, and continuously send real-time data to the maintenance unit, and timely feedback to the scene when problems are found.
The common material of low-pressure casting is A356\ZL101\ZL101A,this kind of material is usually applied to auto part, storage part,transformation part,etc.
The pressure on the surface of the molten metal is 0.06~0.12Mpa.This processing has good shrinkage, casting tissue is dense, easy to produce the large thin-walled complex parts, the casting head is not needed , metal yield can be up to 95%.
Low pressure casting can adopt sand type, metal type, graphite type, etc. The filling process is not only different from gravity casting such as metal casting and sand casting, but also different from high pressure and high speed filling pressure casting, which has the following advantages:
1) Pure metal liquid filling type, which improves the purity of the casting. Because the slag generally floats on the surface of the metal liquid, and the low pressure casting by the metal liquid in the lower part of the crucible realizes the filling through the lifting pipe, which completely avoids the possibility of the slag into the cast cavity.
2) The metal liquid filling type is smooth, reducing or avoiding the turnover, impact and splashing phenomenon of the metal liquid when filling the type, thus reducing the formation of less oxide slag.
3) The casting molding performance is good, the metal liquid filling under the pressure action, can improve the fluidity of the metal liquid, is conducive to the formation of clear outline, smooth surface casting, for the formation of large thin-wall casting is more favorable.
4) The casting crystallizes and solidifies under pressure, which can be fully condensed, and the casting structure is compact.
5) Improve the yield of metal liquid, generally do not need to burst, and the same metal in the lifting tube can be returned to the crucible, reuse, so that the yield of metal liquid greatly increased, the yield can generally reach 90%.
6) Convenient production and operation, good working conditions, high production efficiency, easy to achieve mechanization and automation.
Low pressure casting also has some disadvantages, equipment and mold investment is large; in the production of aluminum alloy casting, crucible and lift pipe long time with metal liquid contact, easy to erosion and scrap, will also make the metal liquid iron and performance deterioration.
Low-pressure Casting Parts,A356 casting parts,A356 low-pressure casting parts,ZL101 casting parts,ZL101 low-pressure casting parts,A356 casting components NINGBO ZHENHAI BOLANG METAL PRODUCT FACTORY , https://www.aldiecastings.com
Low-pressure casting was the earliest anti-gravity casting technology, which was first used in industrial production in the 1940s. Nowadays, low-pressure casting is mainly used in the production of aluminum alloy and magnesium alloy parts, such as the automotive hub of the automobile industry, the cylinder body, cylinder head, piston, missile shell, impeller, air guide wheel and other castings with complex shapes and high quality requirements.
The latest classification of gas compressor shaft device transfer prediction maintenance and analysis
From the monitored axial trajectory map, there are no signs of abnormal mutations.