Views:513 Author:Site Editor Publish Time: 2019-07-25 Origin:Site
A needle bearing is a roller bearing with a cylindrical roller. Today we will introduce how to install needle bearings.
For needle roller bearings without inner ring or outer ring, when installing, first apply a thin layer of grease to the rolling surface of the shaft or housing hole, and then apply the needle to the grease on the installation site. The gap should be left when the last needle is placed. The size of the gap is preferably 0.5 mm on the circumference of the needle bearing.
Never squeeze the last needle into it, or install a needle less, because the bearing will be stuck and cannot rotate when it is hard-pressed; when it is less loaded, the gap is too large, which will cause the bearing to run. The needle is twisted and broken. In particular, it is pointed out that for needle bearings with only the outer ring, since the outer ring wall is very thin, it is best not to use a hammer to install it, and it should be pressed with a press. Because the pressure is not uniform when the hammer is struck, it is easy to cause local deformation of the outer ring of the needle bearing.
The installation of a full complement needle roller bearing is usually carried out using an auxiliary sleeve. At this time, the auxiliary roller or the auxiliary sleeve holds the needle without causing the needle to fall out, and the journal pinch the needle with its own chamfer. As the needle bearing moves slowly inward on the journal, the auxiliary roller Or the auxiliary sleeve will slowly withdraw until it is placed in the working position.
The outer diameter of the auxiliary roller and the auxiliary sleeve should be smaller than the shaft diameter by 0.1 to 0.3 mm. When installing, first apply the grease to the inner surface of the outer ring of the bearing, and place the needle on the inner surface (there should be a gap when placing the last needle), and then replace the auxiliary roller that replaces the journal or the inner ring of the bearing. Or the auxiliary sleeve is pushed into the outer ring hole, and the end surface is aligned with the end surface of the mounting shaft or the end surface of the bearing inner ring that has been mounted on the shaft, and then the pressure is applied by a press or a hammer.
The cause of damage to the needle bearing can be said to be basically due to excessive use time, too little lubricant and contaminants. In general, 33.3% of needle roller bearings were damaged due to fatigue damage, 33.3% of needle roller bearings were due to poor lubrication, and 33.3% were due to improper entry of contaminants into bearings or equipment.
1. If there is a lot of dust around the needle bearing, it will increase the wear of the components between the bearings and reduce the service life of the bearing. Therefore, it is important to keep the cleaning around the needle bearing.
2. Lack of lubricating oil can lead to increased friction and increase the frequency of machine failure.
3. It is not installed with professional installation tools. Professional tools can reduce the contact between needle roller bearings and fibers, making the bearing life longer.
The tapping force is generally added to the inner ring of the bearing. The knocking force of the shielding machine room should not be added to the rolling element and the cage of the bearing. This method is simple and easy, but it is easy to damage the bearing. When the bearing is at the end of the shaft, the bearing is smaller than the bearing. The inner diameter of the copper rod or other soft metal material is pressed against the shaft end, and the lower part of the bearing is padded, and can be removed by tapping with a hand hammer. Apply this method should pay attention to the position of the spacer should be appropriate, the focus should be correct.
Used to remove the tight fit bearing. First, the oil heated to about 100 °C is poured into the bearing to be dismantled. After the bearing ring is thermally expanded, the bearing can be pulled out with a puller.
Pushing the bearing with a press, the work is stable and reliable, and does not damage the machine and the bearing shielding machine room. The press has manual pushing, and the mechanical or hydraulic press pushes. The focus of the press should be on the center of the shaft and must not be biased.
A special puller is used. When disassembling, the bearing will be pulled out slowly as long as the handle is rotated. When the outer ring of the bearing is disassembled, the angle of the two legs of the puller should be opened outwards; when the inner ring of the bearing is removed, the two legs of the puller should be inward and snapped onto the end face of the inner ring of the bearing.
Needle roller bearings are equipped with thin and long rollers, which are compact in radial structure and have the same inner diameter and load capacity as other types of bearings. They have the smallest outer diameter and are especially suitable for support structures with limited radial mounting dimensions. Needle roller bearings should be combined with bearing rings and applications depending on the application. A needle bearing is a bearing unit that combines a radial needle bearing and a thrust bearing component.