Bearing surface rust pretreatment method: 1, surface cleaning: cleaning must be combined with the properties and the conditions of the timken bearing surfaces.
Methods are usually used solvent cleaning, mechanical cleaning and chemical cleaning method.
2, the surface after dry clean dry compressed air to blow dry available filtering.
Or use dryer to 120 ~ 170 ℃ temperature drying, the final use clean cloth to wipe dry.
Outside the spherical bearing lubricating oil of the normal use of color is brown and dark blue.
If a part, it shows that the oil blended with diesel or moisture, should be replaced in a timely manner.
If dark black, it showed that the oil has been bad, must be timely replacement.
The thesis& oil drops after stir in white paper (
It's best to filter paper)
, form the oil stain, staining outward from the center after about 2 ~ 3 hours of gradually spread, form three concentric rings.
According to the color of the three regions, size and shape can identify the state of the oil.
From the lower shell oil with a little oil, besmear is on the fingers, fingers and thumb twist mill.
If you have any impurity or feel oil like water without a sticky feeling, even send acerbity or have a sour taste, oil has been bad.
If twist after grinding on the finger to see small shiny metal grinding, the serious wear and tear parts, engine are also shows that the oil must be replaced immediately.
1.
Bearing grinding heat outer spherical bearing grinding, grinding wheel and workpiece contact zone, consume large amounts of energy, to produce a large number of grinding heat, local transient high temperature caused by grinding area.
On the basis of the theory of linear motion heat source heat transfer formula derivation, calculation or by the method of infrared ray and measured experiment under the condition of instantaneous temperature thermocouple method, can be found in 0.
1 to 0.
The grinding area within 001 ms instantaneous temperature up to 1000 ~ 1500 ℃.
The instantaneous high temperature, which would have made certain depth on the surface of the work surface to produce high temperature oxidation, amorphous group, high temperature tempering, secondary hardening, and even burn cracking and other changes.
(
1)
Surface under the action of transient high temperature oxide layer of the surface of the steel and the oxygen in the air, rises into extremely thin (
20～30nm）
The iron oxide thin layer.
It is worth noting that the oxide layer thickness and surface grinding metamorphic layer is the total thickness test results in corresponding relation.
This shows that the thickness of oxide layer, is directly related to the grinding process is an important symbol of grinding quality.
(
2)
Amorphous layer organization grinding the instantaneous high temperature makes the workpiece surface reach a molten state, molten metal molecular flow is evenly coated to the work surface, and the matrix metal cooling at breakneck speed, formed a very thin layer of amorphous tissue layers.
It has high hardness and toughness, but it is only about 10 nm, it is easy to be removed in the precision grinding processing.
(
3)
High temperature tempering instantaneous high temperature can make the surface layer of grinding zone certain depth (
10 ~ 100海里)
Be heated to a temperature higher than the workpiece temperature tempering heat.
In the absence of austenitizing temperature reached, with the improvement of heated temperature, the surface will produce one by one and heating temperature corresponding to the organization transformation, or high temperature tempering tempering hardness.
The higher the heating temperature and hardness of the decline is more severe.
(
4)
Transient high temperature quenching layer when the grinding area on the second floor heat the workpiece surface layer to the austenitizing temperature (
Ac1）
Above, the layer of austenitizing group in the subsequent cooling process, the quenching into martensite structure anew.
Where the secondary hardening burns of workpiece, the second time hardening layer must be under very low temperature tempering hardness layer.
(
5)
Grinding crack two quenching burns will make workpiece surface layer stress changes.
Secondary hardening zone is in compression state, the high temperature materials back to the fire area underneath there are the largest tensile stress, this is the place where the most likely to occur crack core.
Crack is the most easily spread along the original austenite grain boundary.
Serious burns can lead to crack of the grinding surface (
Formed a crack)
Artifacts caused by scrapping.
Timken bearings or component due to the force change size or shape is called deformation.
The scene of the production machinery and equipment because of the bad working conditions, are often overloaded operations, some outer spherical bearing deformation is very common.
Their deformation will lead to accelerated wear and other related parts and even rupture, and may lead to system series bearing damage or damage to the device, caused the accident, so the harm of deformation is quite serious.
At full load and overload of machinery and equipment for a long time, the temporary load rate already exceeds the provisions of the factory design index, lead to deformation of the bearing.
Steel rolling workshop finished products across the bridge crane, for example, temporary load rates tend to be more than 70%, part bridge girder downwarping bend, and lead to deformation of car body and the four wheels running, screeched friction scream.
Timken bearings in the applied stress is less than the material yield strength when the deformation is called elastic deformation.
Plastic deformation, also known as permanent deformation, is refers to the outer spherical bearing parts in the external force (
Load)
After removing, cannot recover part of the deformation.
Excessive deformation is an important type of machinery and equipment failure.
For example, the bridge crane girder, new purchase and install all have a certain amount on the arch.
After put into production use five or six years, especially the use of high frequency conditions, its main girder arch will disappear.
According to the requirements of enterprise safety procedures, the crane can't continue to use, repair should be performed to eliminate the deformation of main girder downwarping.
Transmission system in some complicated shape and high position accuracy of, measurement and calibration are relatively difficult fundamental components, their deformation will cause a chain reaction.
Mill, for example, the main reducer box body in a column presents the micro deformation, if the position of the shaft will affect the high or low speed, the position of the center distance of the gear reducer, external coupling, gear meshing and so on.
It is conceivable, if these key parts change, will inevitably cause vibration and noise, wear, temperature rise, even broken teeth and accident.
