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The bearing ring raceway is the workpiece surface of th […]
The bearing ring raceway is the workpiece surface of the bearing, and its quality will directly affect the working performance and service life of the bearing. In the process of use, we will often find some common quality problems on the surface of the bearing ring. How do such quality problems arise?
1. Poor surface roughness
Causes: Insufficient ultra-finishing time, high grinding stone pressure, relatively high grinding stone vibration frequency, and low speed of precision and ultra-finishing workpieces.
The convex particles of different sizes and shapes formed on the machined surface after ultra-finishing are mainly due to the fact that the grinding particles are sintered on the machined surface under the action of instantaneous high temperature and high pressure. Their existence increases the vibration value of the bearing and reduces the the service life of the bearing.
Cause: The grindstone pressure is too high. The surface roughness value before superfinishing is too high, the speed of the workpiece is too high, the cooling of the cutting lubricant is insufficient, and the remanence of the bearing ring grinding process is too large.
Mesh scratches on the machined surface after superfinishing.
Causes: There are too many impurities in the grindstone, and the particle size is uneven; the cutting fluid has impurities, and the flushing is insufficient.
4. Comet scars
During the ultra-finishing process, due to the individual larger diamond particles falling off or blocking the low recesses on the surface of the workpiece, comet marks are formed with the ultra-finishing pressure and the rotation of the workpiece.
Reason: Choose the grindstone correctly and reduce the grindstone pressure.
5. Grinding wheel flower
Causes: The grinding wheel is too thick during surface grinding, the workpiece speed is too high during rough and super-finishing, the roughing and super-finishing time is too short, the grinding stone pressure is too small during roughing and super-finishing, and the swing angle of the grinding stone is too small.
6. The axial movement of the end face is too large
Causes: The eccentricity of the workpiece is too small, resulting in unstable rotation of the workpiece, large radial runout, the swing center of the grindstone and the center of curvature of the workpiece raceway do not coincide, and there are debris on the support surface of the end face when the workpiece is positioned, causing the end face to drift axially. The momentum is too large, the geometric accuracy of the grinding process is not good, and the workpiece has been repaired many times.
7. The roundness and waviness are not good
Causes: The eccentricity of the workpiece is too small; the speed of the fine and ultra-finishing workpiece is too large, causing the machine tool to vibrate; the width of the grindstone is not enough, and the wrap angle is too small; the support angle of the roller bar is too small to drive the ferrule to rotate normally; grinding The roundness and waviness of the process are too large.
8. The curvature of the ball bearing raceway is not good after super-finishing
Cause: The swing center does not coincide with the raceway curvature center: the width of the grindstone is too large, and the wrap angle is too large.