Bearing ring raceway is the surface of bearing workpiece, its quality will directly affect the bearing performance and service life. In the use of the process, we will often find some common bearing ring surface quality problems, so how the quality problem is generated? Small series of years of experience, to tell you the surface of the bearing ring common quality problems and the reason.
1. Poor surface roughness
Causes: the ultra-finishing time is not enough, the grinding stone pressure is too high, the vibration frequency of the grinding stone is relatively high, and the rotational speed of the workpiece is too low.
Convex particles of different sizes and shapes formed on the processed surface after ultra-precision machining are mainly due to the fact that grinding particles are sintered on the processed surface under the action of instantaneous high temperature and high pressure, which increases the vibration value of the bearing and reduces its service life.
Cause: High millstone pressure. The surface roughness is too high, the workpiece speed is too high, the cutting lubrication liquid cooling is not enough, and the remanence of bearing ring in grinding is too large.
Netlike scratches on the surface after superfinishing.
Cause: abrasive too much impurity, particle size is not uniform; Impurity in the cutting fluid, insufficient flushing.
4. Coma star marks
During the superfinishing process, some large diamond particles fall off or plug in the low concave of the workpiece surface, forming coma star marks with the superfinishing pressure and the rotation of the workpiece.
Cause: choose the right grindstone, reduce the grindstone pressure.
5. Grinding wheel flower
Causes: The grinding wheel flower is too coarse during surface grinding, the workpiece speed is too high during rough superfinishing, the rough superfinishing time is too short, the grindstone pressure is too small and the grindstone pendulum Angle is too small during rough superfinishing.
6. The axial channeling momentum of the end face is too large
Causes: the workpiece eccentricity is too small, resulting in the workpiece rotation instability, the radial circle is large, the grinding stone swing center and the workpiece raceway curvature center do not coincide, the workpiece positioning end surface support surface debris, resulting in the axial movement of the end surface momentum is too large, grinding process geometric accuracy is not good, the workpiece after several repairs.
7, roundness, waviness is not good
Causes: the workpiece eccentricity is too small; The machine vibrates when the speed of the workpiece is too high. The width of the grindstone is not enough, the Angle is too small; When the roller is positioned, the supporting Angle is too small to drive the ring to rotate normally. Grinding process roundness, ripple over large.
8. The raceway curvature of ball bearing is not good after raceway superfinishing
Causes: The swing center does not coincide with the raceway curvature center: the width of the grindstone is too large, and the wrapping Angle is too large.