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Xi'an Institute of Aeronautical Technology, College of Engineering, College of Library, Three Generations of Main Battle Tanks, Motor Oil Pumps, Gear Wear, Analysis of Guo Wenjun (Xi'an Aeronautical College, Xi'an 710077, China). The results were analyzed to find out the causes of oil pump gear wear and the impact of gear wear. Factors have been proposed to reduce gear wear and improve measures.
According to the technical agreement signed by the Xi'an Aeronautical College and the North China Vehicle Research Institute in July 1995, the Xi'an Aviation Academy's factory provides the three-generation main battle tank motor oil pump (hereinafter referred to as the third-generation oil pump) to the North China Vehicle Research Institute. To this end, after more than four years of hard work, the factory has made major improvements on the basis of the original CB-39 oil pump, which has improved the pressure and flow, and passed the initial sample test, the prototype test, and the hot zone test. The 10,000-kilometer driving test and the National Day military parade test, the performance of the oil pump reached the tactical technical requirements of the three-generation main battle tank. On the 50th anniversary of the National Day, the three generations of main battle tanks successfully passed through Tiananmen Square and accepted the inspection of the party and state leaders. As an important accessory product of the three generations of main battle tanks, the motor oil pump is indispensable.
In order to check the adaptability of the three generations of oil pumps in long-term complex environment, to assess their correct and measurable performance, and to prepare for the design of the mainframe, 10 sets of three-generation oil pumps will be installed on the prototype car with a test of 10,000 km. Perform decomposition identification. This work was carried out in accordance with the GB59.48 armored vehicle test procedure and was completed in mid-May 1999.
The blue layers of the bearings at the ends of the main and passive gears of the nine three-generation oil pumps have slightly different wear marks, and the passive gears are more than the drive gears. There is no wear mark on the bearings at the two ends of the main and passive gears of one oil pump, and the blue layer is intact, but it is a CB-39 type oil pump.
The passive gear of the 10 pumps is on the plane end side of the pump cover, the blue layer is polished, and the rotation of the gear is left on the plane of the pump cover. The rotation trace at the driven gear is more obvious than that at the drive gear.
After the decomposition, the dimensions of the pump body, the pump cover, the driving gear and the driven gear are measured, and the results are as shown in the figure.
According to the test results, 40 pairs of gears have been tested for 40 size segments. Only one of the drive gears has a short shaft end dimension of 0.005 mm. The rest of the dimensions are within tolerance, but the number of passive gears is close to the lower one than the drive gear. .
From the results of the test, it is known that 10 pairs of pump bodies and pump covers have been tested for 40 size segments, and three pump bodies have a hole diameter of 001 millimeters, and the diameters of the two pump covers are 0.001 mm.
a) The main young, I am, I am 4, C) Sang, the younger, the wheel, the hole, the book, the third, the chestnut, the younger, the hole, the gear, the pump, the pump, the pump, the pump, the pump, the pump, the pump, the pump, the pump, the pump Intermittent work. Work for a few minutes each time, and then work after the shutdown.
The working medium of the oil pump is lubricating oil. At the same time as the lubricating oil is sent to the main engine, it is also lubricated and the working conditions are good.
According to the above characteristics, and the mileage of the driving test is not very long, the wear of the gear is extremely slight, and most of them are in the initial wear stage of the entering. Therefore, compared with the wear of the general machine parts, the amount of wear in the same time is much smaller than that of the general machine.
Through decomposition, visual inspection and test results, it can be seen that after the 10000km driving test, the pump body, the pump cover, the driving gear and the driven gear have different degrees of wear. The main reasons for wear are as follows: 03 lubricating oil hole in the driving gear hole of the pump body, during the processing, the pore size is small and deep, the residual burr is not cleaned, the sharp edge is not blunt, and when the gear rotates at high speed, these burrs The debris and sharp edges cause the matching of the driving gear and the pump body to be scratched and the surface is worn. But this is abnormal wear and can be avoided.
The chemical composition of the material is poorly uniform and the surface has hard spots. When the gear rotates at an idle speed, these hard spots will draw fine lines on the surface of the inner surface of the chestnut body or the pump cover, and cut fine particles, which remain in the joint between the gear and the pump body or the pump cover, and further rotate with the rotation of the gear. The gear and the pump body or the inner surface of the pump cover act to cause the blue layer to be polished and the aperture to be enlarged, which is normal wear and is inevitable.
There are many factors affecting gear wear, mainly metal materials, flow and pressure, speed and viscosity.
The composition of the metal material and its internal tissue state have a great influence on the wear of the workpiece. As far as the material selected for the gear is concerned, it is inevitable that there are tiny hard spots on the surface of the workpiece, such as hard particles such as carbide. These tiny hard spots can scratch the mating surface and cause wear. The more hard spots, the sharper the shape and the more wear and tear. The internal structure of the metal material has a certain influence on the wear of the grain thickness. The finer the crystal grains, the more the number, the more uniform the distribution, the better the wear resistance of the material, and the smaller the wear.
The flow and pressure of the three generations of oil pumps are larger than those of the CB-39 type oil pumps. From the influence of the flow rate on the bearing load, the oil pump with a certain gear diameter increases the tooth width and the flow rate also increases. As the tooth width increases, the pressure receiving area increases, and the bearing load also increases. To keep the gear bearing load constant, the pump pressure decreases as the tooth width increases, which is clearly not in line with the requirements. Therefore, as the flow rate increases, the load on the bearing must increase, and the wear must increase. The flow rate of the third-generation oil pump is larger than that of the CB-39 type oil pump. According to the force situation, according to the gear hydraulic pump operation, the radial load on the driven gear is always higher than that acting on the driving gear. The radial load is large. Visual and test results prove that this analysis is correct. Therefore, the first possible wear and tear is the passive gear, which is worn more than the drive gear, whether it is a CB-39 oil pump or a three-generation oil pump. The pressure of the third-generation oil pump is 22% larger than that of the CB-39 oil pump, and the radial load is 68%. Since the flow and pressure of the three-generation oil pump are larger than the flow and pressure of the CB39 oil pump, the radial load of the gear is also large. Wear should be severe.
The speed affects the life of the gear. Regardless of the three-generation oil pump or the CB-39 type oil pump, they are all low-pressure pumps, and the light load is not large. Therefore, the gear is directly supported on the housing hole, and the load is supported by the liquid power oil film. In order to prevent the oil film from rupturing, the gear directly contacts the inner hole of the housing to cause wear, so it is necessary to limit the excessive rotation speed. At the same time, in order to prevent the oil temperature from being too high, the viscosity is too small, affecting the filling of the liquid between the teeth, accelerating the wear, and also limiting the speed of the excessive enthalpy. (Go to page 46) Training issues, solve the theory combined with practical problems, develop hands-on ability, initially contact industrial production, and complete the first engineering training after the students learn. Take the metalworking internship as an example: a student who knows nothing about metalworking, after two weeks of internship, learned about the process of sand casting and special casting, as well as the equipment of free forging and die forging, the process of processing forgings and welding. Some basic contents have a preliminary understanding of the practical knowledge of why heat treatment can change the performance of steel. Actively create conditions to strengthen the alliance with enterprises, and establish a combination of teaching, research and production, so that students have more opportunities to participate in production practice during the study period, and promote the training of students' practical skills. Enhance the ability to adapt to actual work. This will have a good impact on the graduation of students to work.
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