The sliding bearing is in surface contact, so the contact surface maintains a certain oil film, so pay attention to the following problems when designing:
1, the oil film can smoothly enter the friction surface.
2. Oil should enter the bearing from the non-load bearing area.
3. Do not let the entire annular tank open in the middle of the bearing.
4, such as oil bricks, seams open the oil groove.
5, making the oil ring to the oil is completely reliable.
6, do not block the oil hole.
7, do not form an oil no-flow area.
8, to prevent cutting off the sharp edges and edges of the oil film.
Sliding bearings can also be lubricated with grease. The following points should be considered when selecting grease:
(1) When the bearing load is low, a small amount of grease should be used for penetration, and vice versa, and the taper is selected to be large. High-speed bearings are used for small tapping and good oil stability. It is important to note that the viscosity of the grease base oil is low.
(2) The choice of grease is generally higher than the working temperature of 20-30 ° C, in the case of continuous operation at high temperatures, be careful not to exceed the allowable grease temperature range.
(3) When the sliding bearing works in water or humid environment, it should choose good water resistance, calcium, aluminum or lithium grease.
(4) Use good grease adhesion.
2, the choice of sliding bearing grease:
The load is <1MPa, the circumferential speed of the journal is less than 1m / s, the maximum working temperature is 75 °C, and the calcium on the third grease is selected;
The load is 1-6.5MPa, the circumferential speed of the journal is 0.5-5m / s, the maximum working temperature is 55 °C, and 2 calcium-based greases are used.
Load > 6.5MPa, the circumferential speed of the journal is less than 0.5m / s, the maximum working temperature is 75 °C, and the No. 3 calcium-based grease is used;
The load is <6.5MPa, the circumferential speed of the journal is 0.5-5m / s, the maximum working temperature is 120 °C, and 2 lithium-based greases are selected.
Load > 6.5MPa, outer peripheral speed 0.5m / s or less, maximum working temperature 110 °C, use 2 calcium calcium sodium grease;
The load is 1-6.5MPa, the circumferential speed of the journal is less than 1m / s, the maximum working temperature is 50-100 °C, and two kinds of lithium-based greases are used.
Load > 5MPa journal circumference speed 0.5m / s, maximum working temperature 60 °C, select No. 2 calendar grease;
In a humid environment, calcium-sodium grease should be applied at a temperature of 75-120 °C. In a humid environment, the working temperature is lower than 75 ° C, does not contain 3 calcium-based grease, and can also be used as aluminum alloy grease. The working temperature is 110-120 ° C, using lithium grease or sulfhydryl grease. Concentrated lubrication, less consistency.
3, sliding bearing grease lubrication cycle:
Unexpected work, important parts: shaft speed <200r / min, lubrication cycle once every 5 days; shaft speed > 200r / min, lubrication cycle once every 3 days.
Intermittent operation: shaft speed <200r / min, lubrication cycle 2 days; shaft speed > 200r / min, lubrication once a day.
Continuous operation, working temperature less than 40 °C: shaft speed <200r / min, lubrication cycle once a day; shaft speed > 200r / min, lubrication cycle once.
Continuous operation, working temperature 40-100 °C: shaft speed <200r / min, lubrication cycle once; shaft speed > 200r / min, lubrication cycle twice.
It is necessary to make the journal and the sliding bearing uniform and in good contact, but also have a certain gap.
Refers to the angle of contact between the journal and the sliding bearing and the center. The contact angle should not be too large or too small. If the contact angle is too small, the pressure of the sliding bearing will increase, which will cause the sliding bearing to produce more deformation, accelerate the wear and shorten the service life; if the contact angle is too large, the formation of the oil film will be affected, and the liquid lubrication is not good.
Experimental studies have shown that the sliding bearing has a contact angle limit of 120°. When the sliding bearing wears to the contact angle, the liquid lubrication is broken. Therefore, the sliding bearing is no longer affected under pressure conditions, and the contact angle is as small as possible. From the theoretical analysis of friction, it can be seen that when the contact angle is 60°, the friction torque is the smallest. Therefore, it is recommended that the rotational speed of the sliding bearing is higher than 500r / min, the contact angle is 60°, the speed is less than 500r / min, and the contact angle is It can be 90° or 60°.
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