It is necessary to make the journal and plain bearings even close contact, but also have a certain gap with.
Contact angle refers to the journal and the bearing contact surface of the center angle. Contact angle can not be too large nor too small. Contact angle is too small will increase the pressure on the sliding bearings, will result in serious deformation of the sliding bearings in severe cases, accelerated wear and shorten the service life; contact angle is too large, will affect the formation of oil film, not good liquid lubrication.
Experimental studies show that the contact angle of the plain bearing is 120 °. When the sliding bearing wear to this contact angle, liquid lubrication will be destroyed. Therefore, under the premise of not affecting the pressure condition of the sliding bearing, the smaller the contact angle, the better. From the theoretical analysis of the friction distance, when the contact angle is 60 °, the friction torque is the minimum. Therefore, it is suggested that for the sliding bearings with the speed higher than 500r / min, the contact angle is 60 ° and the speed is lower than 500r / min. The contact angle can be 90 ° or 60 °.
Contact point
The actual contact between journal and plain bearing surfaces can be expressed in terms of actual number of contacts per unit area. More contact points, the more detailed, more uniform, that the better the sliding bearing scraping research, on the contrary, it means sliding bearing scraping research is not good. In general, the more contact points, the more difficult scratching.