Tapered roller bearing heat treatment of adverse life cause analysis

Tapered roller bearing parts work surface and center in the state, there is a large difference in structure and performance requirements, and the overall heat treatment often cannot give attention to two or morethings, material it is hard to give full play to their potential. Applied materials surface strengthening technology can not only solve the surface and center differences in structure and requirements, but also can make further surface to obtain specific performance, in order to meet the work under certain conditions on the properties of working surface of bearing requirements. So the surface strengthening technology can be classified from different Angle to form a variety of methods, according to the chemical and physical process of surface strengthening technology classification, can be roughly divided into five categories: surface deformation strengthening heat treatment, surface strengthening, the chemical heat treatment, surface metallurgy strengthening, film surface strengthening. Refers to the relative sliding friction between the surface abrasion failure lead to constant wear and tear of the working surface of the metal and the failure. Continuous wear will cause TIMKEN bearing parts gradually damaged, and the ultimate result in the loss bearing dimensional accuracy and other related topics. Wear may affect the appearance change, the increase of fit clearance and working surface morphology change, may affect the lubricant or make its pollution to a certain degree of lubrication function is lost, so that loss of bearing rotating accuracy and will not operate properly. Wear failure is one of the common failure modes of all kinds of bearings, according to the wear and tear is usually divided into one of the most common form of abrasive wear and adhesive wear. Contact fatigue failure refers to the bearing working surface under the role of alternating stress and failure. Contact fatigue spalling occurred in bearing working surface, is often accompanied with fatigue crack, first of all, from the maximum cyclic shear stress under contact surface, and then extended to form a different flake shape, such as dot to pitting corrosion or pitting spalling, peel into small sheet according to the shallow flaking. Because spalling surface expands gradually, and often to deep extension, forming deep spalling. Deep spalling is the exhaustion of contact fatigue failure of the source. TIMKEN bearing failure of the main reason is that defects and overload two factors. When the loads more than material strength limit fracture caused by parts called overload fracture. Overload reason mainly is the main engine failure or improper installation. Bearing parts of micro crack, shrinkage cavity, bubbles and large foreign impurities, overheating organizations and local burns and other defects during the impact overload or violent vibration will cause fracture in defect, known as defect fracture. It should be pointed out that the bearing in the process of manufacturing, for raw materials into the factory reinspection, casting and heat treatment quality control, process control through accurate analysis instrument in the existence of the above defects and the future is still necessary to strengthen control. But in general, most of bearing failure for overload usually fail. Bearing in the work, because of external or internal factors, change the original fit clearance, lower accuracy, and the change of 'killed' called clearance failure. , large amount of the external factors such as interference of installation does not reach the designated position, temperature rise caused by the expansion, instantaneous overload, etc. , internal factors such as residual austenite and residual stress is in not not disorderly state changes are caused by clearance of the main causes of failure.