1. Installation and detection of bearing shells and contact area between the back of the bearing shell and the bearing seat
Firstly, clean the contact surface between the body tile seat and the back of the bearing shell, and apply a display agent in the arc of the body tile seat. Then, install the two lower tiles in the tile seat and rotate them back and forth at a certain angle. After Z, lift out the lower tile and check the contact between the tile back and the tile seat. If the contact area reaches 70% or more, it means that the two are well matched. If the contact area is less than 70%, the lower tile will easily produce angular deviation during equipment operation. Therefore, it is necessary to scrape the tile back to make its contact area reach 70% or more.
2. Scrape the bearing shell
The procedure for scraping tiles is to first scrape the lower tile roughly and finely, then scrape the upper tile roughly and finely, and finally scrape the entire tile finely. After Z, scrape the side clearance and oil storage points.
2.1 Coarse and fine scraping of lower tiles. Firstly, install the two lower tiles in the tile seat of the machine body and keep them basically horizontal in the horizontal direction. Then, place the gear shaft in the two lower tiles and rotate it 2-3 times along its normal operating direction. Measure the levelness of the gear shaft, and after Z, lift it away. At this time, based on the contact between the shaft neck and the two tiles and the relative elevation of the two tiles, rough scraping of the two tiles can be started simultaneously. When rough scraping, the levelness of the gear shaft should be considered first. The first few times of rough scraping, the cutting method should be heavy, and the movement distance of the knife should be 30-40mm. During the rough scraping process, all the basic curved surfaces should be scraped off, and scraping is not allowed if there is no contact. When the contact between the two tiles reaches about 50% of the lake surface and the levelness of the gear shaft is within 0.25mm/1000mm, the rough and fine scraping work of the lower tile is completed.
2.2 Coarse and fine scraping of tiles. The methods and requirements for coarse and fine scraping of the upper tile are basically the same as those for coarse and fine scraping of the lower tile. The difference between the two is that the upper tile should be placed on the gear shaft for grinding, so they are omitted.
2.3 Fine scraping of upper and lower bearing shells. After rough and fine scraping, the upper and lower bearings have contact spots within the contact angle, but the contact spots are large and further fine scraping is needed. At this time, according to the method of measuring the top clearance of the bearing shell introduced in the third part below, the thickness of the pad on the joint surface of the bearing shell should be calculated, the bolts should be tightened, and the gear shaft should rotate 1-2 turns in its normal operating direction. Then, the upper bearing should be removed, the gear shaft should be lifted away, and Z should be used for fine scraping of the larger points until the contact points on the contact surface are no less than 4-5 points per 25mm × 25mm area.
2.4 Scrape the side clearance. After the fine scraping is completed, the part outside the 120 ° contact angle should be scraped off, but a portion should be left at both ends to prevent oil from flowing out from both sides of the bearing, thus ensuring liquid lubrication of the bearing. When scraping the side clearance, there should be no clear boundary between the contact and non-contact parts of the bearing, and a smooth transition should be made.
2.5 Scrape and store oil points. After the above work is completed, it is advisable to scrape the oil storage point on the contact arc surface of the bearing. The function of the oil storage point is to store lubricating oil and accumulate dirt to ensure good lubrication conditions of the bearing. The oil storage point can be scraped into a circular or flat shape, with a depth of generally 0.3-0.5mm and an area of 15-30mm2. Its area should not exceed 1/5 of the contact arc surface. When scraping the oil storage point, it should be smoothly transitioned with the bearing surface.
3. Measure the clearance between the bearing shells
The clearance between bearing shells is divided into radial clearance and axial clearance. The radial clearance is divided into top clearance and side clearance. The top clearance should be the lower difference of the design fit tolerance between the shaft and the bearing shell, the side clearance should be 80% -100% of the top clearance, and the axial clearance should be 1-3mm.
3.1 Measurement of top clearance. Before the precision scraping of the bearing, the top clearance of the bearing should be measured once. After the scraping of the bearing is completed, to determine the thickness of the gasket on the joint surface of the bearing, it must be measured again. Generally, the lead pressure method is commonly used to measure the top clearance of the bearing (see figure). The measurement and calculation process is as follows:
(1) Dismantle the upper tile; (2) Place soft lead wires or strips with a diameter of 1.5-2 times the clearance value and a length of 20-50mm on the joint surface between the journal and the bearing shell respectively; (3) Close the upper bearing, apply the locating pin, evenly tighten the bolts, and use a feeler gauge to check the joint surface of the bearing, ensuring that the clearance values are basically equal; (4) Remove the tile and measure the thickness of the flattened soft lead wire with a micrometer; (5) Calculate the average top clearance of the bearing shell: △=(a1+a2+a3)/3- (b1+b2+b3+b4+b5+b6)/6 (△ - the average top clearance of the bearing shell; A1+a2+a3- the thickness value of each section of soft lead wire flattened on the shaft neck; B1+b2+b3+b4+b5+b6- the thickness value of each section of soft lead wire flattened on the joint surface of the bearing shell. )(6) Calculate the pad thickness of the joint surface, δ: δ=C - △ (where C represents the standard top gap value). )(7) Determine the actual pad thickness of the bearing joint surface. It should be noted that the number of layers of copper pads should be as few as possible, and should not exceed 1mm thick copper skin.
3.2 Measurement of side clearance. The side clearance between the bearing shell and the journal is usually measured using a feeler gauge. When measuring, the length of the feeler gauge inserted into the clearance should not be less than 1/4 of the journal diameter.
3.3 Axial clearance measurement. The axial clearance of the bearing shell is generally measured with a feeler gauge.
4. Assembly, adjustment, and testing
After the above-mentioned processes, the bearing can be assembled. During assembly, it is necessary to clean the bearing, journal, oil collector, and lubricating oil pipe. After the bearing and the entire equipment are installed, adjust the coaxiality of the drive motor shaft and input shaft based on the input shaft external reference, and then connect and fix them. Before the test, the test can be carried out. The oil supply station should be turned on first and rotated several times. During operation, the supply of oil should be slightly larger than during normal use. If a significant increase in oil temperature and current is observed during the test drive at noon, it indicates that the quality of the scraping tile is good.
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MG-EPB5Z Plastic Plain Bearings：
MG-EPB5Z Plastic Plain Bearings It is a high load material with excellent low friction factor. Marginal load application is acceptable and it is with good wear resistance both for hard and soft shafts. Continuous working temperature: -100℃～250℃; High load capacity; Higher speed is permissible; Marginal pressure is permissible; Best performance for oscillating movement.
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