Hydrodynamic sliding bearing has the advantages of simple structure, small size, high precision, low vibration and can bear heavy load.
At present, most high-speed rotating equipment and mechanical vehicles are supported by hydrodynamic sliding bearings. Each shaft has two liquid sliding bearings, one of which is a thrust bearing with thrust surface. Hydrodynamic sliding bearing has the advantages of simple structure, small size, high precision, low vibration and can bear heavy load. Under the condition of ensuring the lubricating fluid, it can operate safely at the design speed for a long time. The purpose of bearing scraping is to ensure the clearance between journal and bearing, make it easy to form oil film and ensure the normal operation of the equipment. It is an important part of the maintenance of the whole equipment.
Because the lubricating oil has a certain viscosity, the high-speed rotating shaft continuously brings the lubricating oil from one side of the shaft to the other side of the shaft along the rotation direction through the upper part of the shaft. Under the joint action of external load and lubricating oil, the shaft center will move a distance E in a certain direction, forming a gap from large to small between the shaft and the working surface of the bearing, that is, oil wedge. The rotating shaft makes the oil continuously squeeze from the large end of the gap into the small end, resulting in the balance between the lifting pressure of the shaft and the external load. The journal and the working surface of the bearing are separated by an oil film, that is, liquid dynamic pressure lubrication is realized.
First, clean the bearing with kerosene, gasoline or other cleaning agents. Then check whether the Babbitt alloy cast and processed by the bearing has cracks, shelling, sand holes and holes. The method is to tap gently with a copper hammer along the surface of Babbitt alloy in sequence (including the thrust surface of thrust bearing). If it makes a crisp jingle sound, it means that Babbitt alloy is well bonded with the bottom pad and the quality of bearing is good. If it makes a voiced or dumb sound, it means that Babbitt alloy is not well bonded with the bottom pad and the quality of bearing is poor, so it cannot be used.
Check the contact of the split surfaces of the upper and lower bearing shells. The upper and lower split surfaces of the bearing must be flat. Place them on the flat plate and check them with a feeler gauge. If they do not meet the requirements, grind them with fine sandpaper padded with a flat plate below until they meet the requirements.
Check whether the locating pins of the upper and lower bearings are positioned reliably. The size of the locating pin must be consistent with the size of the locating hole, and the assembly cannot be too loose or too tight. If it is too loose, a new locating pin shall be equipped according to the actual situation. If it is too tight, the pin hole shall be machined with a reamer, so as to ensure the reliable positioning of the locating pin. Check whether the oil circuit is unblocked and whether the oil circuit is blocked by Babbitt alloy or other foreign matters. If so, it must be removed, otherwise it will affect the lubrication of the bearing and even burn the Babbitt alloy of the bearing. Recheck the size of the bearing according to the standard, and check the relevant size of the journal to ensure that there is allowance for scraping and grinding in the next step. Check the contact between the bearing and the bearing seat and bearing cover. The spherical surface of the bearing in contact with the bearing seat and bearing cover must contact reliably and meet the specified technical requirements. Otherwise, the spherical surface of the bearing in contact with the bearing seat and bearing cover shall be ground and corrected.
Clean the scraped sliding bearing, bearing seat, bearing cover and oil pipeline. Put the lower bush of sliding bearing into the bearing seat horizontally, and pour lubricating oil on the oil passage and Babbitt alloy. Adjust the amount of interference on the bearing cover. After covering the bearing cover, insert the locating pin and tighten the screws of the upper and lower bearing shells. In order to prevent the sliding bearing from rotating and vibrating in the bearing seat, in addition to installing the locating pin in the bearing and bearing cover, the bearing cover must also produce a certain pressing force on the bearing, which cannot be too large or too small. Too large will deform the sliding bearing and affect the bearing clearance. Too small will easily make the sliding bearing vibrate and the oil temperature rise. The pressing force of the bearing cover on the sliding bearing is usually determined by pressing lead. By adjusting the gasket between the bearing cover and the bearing seat and the sliding bearing, the deformation of the sliding bearing is ensured to be 0.04 ~ 0.08mm.
The fit between the thrust bearing race and the bearing seat hole is generally clearance fit, so this kind of bearing is easier to install. The motion relationship between the bearing and the shaft is mostly driven by the shaft, so the inner hole and the shaft are interference fit, and the outer edge and the seat hole are clearance fit. Generally, the installation method of the bearing is mostly shaft rotation. Therefore, the fit between the inner ring and the shaft is interference fit, and the fit between the outer ring and the bearing chamber is clearance fit.
High speed precision angular contact ball bearing is mainly used in high-speed rotation occasions with light load. It requires high precision, high speed, low temperature rise, low vibration and certain service life. It is often used as the support of high-speed spindle and installed in pairs. The service life of high-speed precision angular contact ball bearing is closely related to the installation. The following matters should be paid attention to: the bearing installation should be carried out in a dust-free and clean room, the bearing should be carefully selected and matched, the bearing spacer should be ground, and the parallelism of the spacer should be controlled at 1 on the premise of maintaining the equal height of the inner and outer spacer μ Below m; The bearing shall be cleaned before installation. During cleaning, the inner ring slope shall be upward, and the hand shall be flexible without stagnation. After drying, put the specified amount of grease. In case of oil mist lubrication, put a small amount of oil mist oil; Special tools shall be used for bearing installation, and the force shall be uniform. It is strictly prohibited to knock. The bearing shall be stored in a clean and ventilated manner without corrosive gas, and the relative humidity shall not exceed 65%. For long-term storage, it shall be regularly rustproof.
More about Marginal Plastic Plain Bearings:
Jiashan Marginal is well-known as one of the leading plastic plain bearings manufacturers and suppliers in China for our quality products and customized service. Please feel free to buy or wholesale bulk plastic plain bearings in stock here from our factory. Contact us for free sample and pricelist. Self-lubricating Bushes, Solid Bronze Turned Bushing, Bronze Wrapped Bushings.
Plastic plain bearings consist of injection-molded functional plastic that can be reworked by turning. The product range is extremely extensive.
Plastic plain bearings that operate with separation of the friction surfaces by a lubricating layer are designed using the hydrodynamic theory of lubrication. The minimum thickness of the lubricating layer (usually measured in microns), the pressure in the layer, and the temperature and flow rate of the lubricating materials are determined in the design computations. Bearings of this type are fabricated from metallic and nonmetallic antifriction bearing materials.
