Machine tool spindle bearings after installation in the host, such as measurement of NSK bearings spindle runout, but found its spin measured value is a certain change; when measured in a row, after can be found after a certain speed, this change will be repeated approximately. Indicator for cyclic running accuracy for measuring such changes, changing approximately the speed required to repeat on behalf of cyclic running accuracy of "cycles", measure changes in the cycle amplitude, cyclic running accuracy is poor.
On the fracture site for scanning electron microscopic observation on high, discover its features have the following several points:
1, magnification observation and micro-morphology of many fan-shaped pattern that is visible.
2, crack the front arc is fatigue, and there is a lot of corrosion pits.
3, different angles fan-shaped pattern morphology of different, different crack connection fan pattern is formed. Observation of crack propagation in a high area, found typical of fatigue cracking on crack source low-scan, you can find Beach source pattern around the crack, crack source areas with significant corrosion pit distribution, some corrosion pits into line, mud pattern morphology.
4, accept the highest stress, to water contact with the cylinder hot-bar. And b the less stress. Water-bearing major recipient of blasting stress at work, stress and thermal stress Assembly of three stresses. Water maximum circumferential stress, its value is about 128MPa is an oil-bearing angular contact ball fire is a random aberration, fire burns exception occurred defects often severe impact the workpiece workpiece appearance quality and performance of our products, or even failure scrap workpiece is not eligible, special appearance important surface precision and quality requirements or even more so.
5, observation found in production, induction heating, artifacts, and fire was often not contact sensors, produced by NSK bearing noise is very sensitive. So in order to maintain smooth operation of the machine tool spindle bearings, the general reliability of sintered bronze oil NSK bearings, but to take some measures, such as proper control of sintering conditions, organization is a single phase a of the alloy and corrosion protection measures may be used; another approach is to make the piece look compressive stress, served to offset the water jacket to withstand the tensile stress.
Be appropriate preload for spindle of machine tool spindle bearings, speed gradually increased to near speed to adopt NSK bearing "break-in" effect can increase the cycles of spindle running accuracy.