1. Requirements for cleaning, inspection and insulation pads
1. Cleaning and inspection of bearing bush
The large motor bearings are shipped in separate boxes. After unpacking, the upper and lower tiles are removed and marked with a ring screw and cleaned with kerosene. Wipe dry with a dry cloth and check whether all grooves are clean and there is no residual casting sand , The tungsten-gold layer is not well combined with the tile body, and the trenches and cracks are marked with sand holes and other dopants, etc.). If it cannot be repaired, tungsten gold should be hung again.
2. Cleaning and inspection of bearing seat
Before installing and locating the bearing housing, a full cleaning inspection should also be carried out. Scrape the dirt inside the bearing housing with a scraper, wipe the dirt with a cloth dipped in gasoline or solvent, and watch for cracks and sand holes to prevent oil leakage during operation. The joint surface of the bearing cap and the bearing seat, the joint surface of the bearing seat and the bearing oil ring should be ground and scraped, and checked with a feeler gauge, the gap should not be greater than 0.03 mm. The surface of the bottom plate where the bearing seat is placed should also be cleaned, and there should be no bruises, rust and burrs. The screws that fasten the bearing seat and the thread of the seat plate should be carefully checked by him, and try to tighten the screws to check whether they are too tight or bare.
3. Bearing insulation structure
Between the bearing and the bottom plate, there must be an insulating backing plate or a metal gasket. The metal gasket is used to adjust the horizontal position of the seat. In order to adjust the relative position of the motor and another motor or machine connected. The metal gasket is made of a thin metal plate of 0.08 ~ 3 mm. The insulation pad is made of cloth laminate or glass fiber laminate. The purpose of placing insulating pads is mainly to prevent the harm of shaft current. Insulation pads should be 5 ~ 10 mm wider than each side of the bearing housing and 3 ~ 10 mm thick. In addition to placing an insulating pad between the bearing and the bottom plate, the screws and studs should also be insulated. The insulating gasket is made of glass cloth with a thickness of 2 ~ 5 mm, and its outer diameter is 4 ~ 5 mm larger than that of the iron gasket. The insulating pad of the oil pipe connecting plate connected with the bearing seat can be made of rubber plate with a thickness of 1 ~ 2 mm. After the installation of the insulated bearing seat, the insulation resistance to the ground should be checked and measured with a 500-volt megohm meter. Its resistance value should not be less than 1 megohm.
Both the single motor bearing and the multi-bearing of the unit should be installed on the main longitudinal axis of the machine or the longitudinal axis of the unit. The bearing center is measured by hanging wire and wire hammer. (A wooden bar is stuck in the bearing arc, and a thin iron bar is nailed in the center of the wooden bar to mark the center position).
Adjust the position of the shaft in the seat, starting from the bearing seat on the side, and use a level to place on the bearing seat surface to check the levelness of these planes. Use theodolite or spirit level to check whether the planes of several shaft seats are in the same horizontal plane, and use line hammers and other methods to find out whether the center of each bearing is on the same axis as shown in Figure 1-5.
Carry out the adjustment work of the bearing base according to the above method. In the process of eliminating the deviation, it should be applied to the jack-type tool to move the bearing base. Do not adopt the method of impact or hammering. Use this method to adjust the precision error of the bearing seat within about 0.5 ~ 1.0 mm. It should be pointed out that the installation and adjustment of the bearing seat is only a pre-adjustment, and it needs to be adjusted when centering to achieve the same requirements of the axis line. After the bearing seat is pre-adjusted, the screws are only tightened evenly (tighten according to the diagonal cycle), and the insulating sleeve and the stabilizing nails can be temporarily held, wait until the centering work is finally completed or before the test drive.
High temperature bearings
Since high-temperature bearing housings must meet the requirements of high-precision stamping bearing housings and high-temperature stamping bearing housings, the following two points need to be considered when considering the fit and clearance of high-temperature bearing housings:
1. Dimensional change and hardness change from normal temperature to high temperature;
2. Changes in force system and shape caused by centrifugal force at high speed.
High temperature bearing seats require that the parts where the stamped bearing seats are installed on the shaft and the seat holes should have higher dimensional accuracy and shape accuracy than the general requirements, especially the coaxiality and the perpendicularity of the shoulder to the seat holes or journals. When considering these issues, we must pay attention to the high-speed factors and high-temperature factors when the high-temperature bearing housing is running.
The high temperature bearing seat is required to have the best clearance under the working state, that is, the working temperature, and this clearance is formed in the state that the center of the inner and outer ring ball grooves are accurately aligned. At the same time, because the high-temperature bearing housing strives to reduce relative sliding and internal friction, it is best not to adjust the clearance of the high-temperature bearing housing by displacing the inner and outer rings in the axial direction.
Post time: May-18-2020