In grinding, grinding wheel and the workpiece contact areas, consume large amounts of energy, a lot of grinding heat, causing local instantaneous temperature of the grinding area. Using the theory of linear motion-heat-source heat transfer formula, calculation or the application of IR method and method of thermocouple measuring instantaneous temperature under laboratory conditions, can be found in 0.1~0.001ms in the grinding zone of instantaneous temperature can be as high as 1000~1500℃. Such instantaneous temperature, sufficient to enable the work surface a certain depth of high temperature oxide layer on the surface, non-crystalline, high-temperature tempering, quenching for the second time, crack even burn and many other changes.
(1) amorphous organization
Transient high temperature of grinding workpiece surface to melt when the molten metal flow is evenly coated on work surface and substrate metal cooling at an extremely fast rate, forming a very thin layer of amorphous organization. It has high hardness and toughness, but it only has about 10nm, easily removed in precision grinding.
(2) surface oxide layer
Steel surface subjected to instantaneous temperature and oxygen in the air, up into very thin (20~30nm) thin-layer iron oxides. Worthy of note is the thickness of the oxide layer and surface grinding of degenerating layer corresponds to the total thickness of test results is related. This indicates that the oxide layer thickness for grinding directly related, are important signs of grinding quality.
A. improper assembly method
Bearing and shaft or housing bore when less interference, use indentation Assembly. The simplest method is to use copper rods and Bishop, according to a certain order of symmetry to knock bearing with interference fit of the seat so smoothly onto the bearing. In addition, also available made of soft metal casing take Bishop to enter or press onto. If improper, then causes the deformation of seat cracked, or Bishop to play on a non-interference fit of the seat, you will have an indentation, or raceways and rolling elements bearing indirect damage.
B. improper temperature control Assembly
When the bearing Assembly, and interference of the larger shaft diameter, generally use and charging method of Assembly. Bearing into the flourishing organic oil in oil drums, external oil barrel with hot water or flame heating, process requirements oil temperature control of heating at 80 ° c ~90 ° c, generally not exceeding 100 ° c, will not exceed 120 degrees centigrade. Rapidly remove packages on the axle bearing after heating. If caused by improper temperature control heating temperature is too high, you will have a tempering hardness caused by lower bearing, run bearing wear, spalling, or even cracking.
C. improper fitting clearance adjustment
Clearance is divided into radial clearance and axial clearance of rolling bearings, its function is to ensure the normal operation of rolling and lubrication as well as compensate for thermal elongation.
For clearance can adjustment of bearing,, due to its axis to clearance and radial clearance Zhijian has are proportion of relationship, so installed is as long as adjustment good axis to clearance on can obtained by needed of radial clearance, and cut they General are is into on using of (that mounted in axis of ends or end), therefore, only needs adjustment a only bearing of axis to clearance can. Gasket adjusting the axial clearance for general use, some also thrust ring screw or adjustment.
For clearance not adjustment of bearing, due to its radial clearance in manufacturing Shi on has by standard determines good has, cannot for adjustment, this class bearing mounted in axis trail Shang or bearing block hole within zhihou, actual of radial clearance called Assembly radial clearance, Assembly Shi to makes Assembly radial clearance of size just can in running in the caused necessary of work radial clearance, to guarantee bearing flexible turn. The bearings in the work, due to elongation of shaft in the heat when the temperature of the seat relative displacement occurs, so that the radial clearance of bearings to reduce, or even rolling stuck in between inside and outside the ring. If double bearing in rolling bearing of a bearing (in another fixed to the shaft and the bearing housings) and allow axial clearance between the side cover to avoid these phenomena.



Other News:
Analysis Spherical roller bearings routine examination preparatory work
Excluded from several aspects of the bearing temperature is too high to start
Improve transport quality of installation of bearing adjustment
Analysis Spherical roller bearings with the selection principles
Problems caused by the complex functioning of FAG bearings
Bearing damage maintenance troubleshooting steps
Bearing boundary grease injection method
How to protect the bearing limit operation