What is the function of bearing cage?
Definition of the bearing cage:
The bearing cage is a bearing part that wraps the rolling elements and moves with it. It is mainly used to isolate the rolling elements and usually guides the rolling elements and keeps them in the bearing.
The function of the bearing cage:
The role of the cage in practical applications: 1. The effect of the cage on the speed, such as 81207 bearings, the design limit speed of the brass cage is about 2500r/min, and the design speed of a stamping cage is up to 6000r/min. 2. Keep The effect of frame accuracy on bearing fatigue peeling: When the cage, especially the cast iron cage, is deformed, the rolling elements and the cage form strong friction, the surface of the rolling elements is high, the hardness is reduced, and they peel off under heavy load. 3. The effect of cage structure on service life, for example: When spherical roller bearings CA, CC, or MB are running at high speed, the temperature rise of the bearing is different due to the different cage structure.
The material of bearing cage:
When the rolling bearing is working, the bearing heats and wears due to sliding friction. Especially under high-temperature operating conditions, the action of inertial centrifugal force aggravates friction, wear, and heat. In severe cases, it will cause the cage to burn or break, causing the bearing to fail to work normally. Therefore, in addition to a certain strength, the material of the cage must also have good thermal conductivity, low friction factor, good wear resistance, strong impact toughness, low density, and a linear expansion coefficient close to the rolling element. In addition, the stamping cage needs to withstand more complicated stamping deformation, and the material is also required to have good processing properties. On some extremely demanding cages, some still have a layer of silver.
The types of cage materials are low carbon steel/stainless steel cage, bakelite/plastic (nylon) cage, brass/bronze/aluminum alloy cage, and so on.
1. Die-casting cage:
The raw materials of the die-casting cage are aluminum alloy and brass. The raw materials are melted and poured into the die-casting mold of the die-casting machine, and the cage is die-casted at one time. The casting gate is turned on the lathe. The technical characteristics of this party are:
(1) The cage is directly formed by die casting, which can obtain good geometric shape and dimensional accuracy, without mechanical processing, and high production efficiency.
(2) After die-casting, the metal crystallizes and solidifies, the structure is precise, the surface quality is good and wear-resistant.
(3) The material utilization rate is high and the cost is reduced.
However, when die-casting aluminum alloy cages, large-tonnage equipment is required, and the mold design and manufacturing are complicated, and the cage pockets are easily damaged during die-casting. Under the condition that the bearing is subjected to shock, vibration and speed change, it is necessary to further improve the quality of the die-cast cage.
2.Plastic casting cage
Put the vacuum-dried granular engineering plastics in a barrel, heat it with resistance wire to melt into a semi-liquid state, pressurize with a plunger or a moving screw, so that the semi-liquid raw material is injected from the nozzle into the forming mold of the injection molding machine, and it is insulated, Obtain the required cage after cooling. The characteristics of his craft are:
(1) The cage can be formed by one-time injection molding, which can obtain precise geometric shape, dimensional accuracy, and low surface roughness value, without mechanical processing, and high production efficiency.
(2) Mold and plastic casting are simple, the bearing assembly is convenient, and automatic control is easy to realize.
(3) The plastic cage has good properties such as wear resistance, antimagnetic and low friction.
However, due to the shortcomings of the plastic itself such as thermal deformation, aging, and brittleness, as well as some problems in the cage structure and plastic injection technology, the application of the plastic cast cage is limited.