Adjust the balance of grinding wheel
The causes of the imbalance:
A grinding wheel is an uneven object. When running, the vibration caused by the center of mass does not coincide with the center of the rotating shaft, which causes the problem of imbalance of the grinding wheel.
Unbalanced situation analysis:
Figure 4-5 Schematic diagram of several states of balance and imbalance of the grinding wheel
The wheel is divided into equal parts by the plane of the vertical axis. The center of gravity of these two parts is A1and A2. According to the position of the center of gravity, there are several imbalances:
The centers of gravity A1, A2 are on the same plane as the center of rotation and are on the side of the centerline. In the static imbalance test, the heavy side stays at the bottom.
The centers of gravity A1 and A2 are on the same plane as the center of rotation and are symmetrically distributed on both sides of the centerline. Therefore, the total center of gravity of the grinding wheel is still located on the centerline of rotation and thus is a static balance, but a force couple (caused by centrifugal force) is generated when rotating, and this couple is only generated when rotating, so it called dynamically unbalanced.
The centers of gravity A1 and A2 are located on different planes, and there are static imbalances and dynamic imbalances. This is the case with actual grinding wheels.
Both A1 and A2 are located on the centerline of rotation, and there is no static imbalance or dynamic imbalance. This is an ideal state.
The harm of imbalance:
- It affects the strength of the grinding wheel shaft and increases fatigue stress.
- The bearing is abnormally worn.
- The grinding wheel vibrates and the machining accuracy decreases.
- The stress of the grinding wheel has been increased and the wheel is easily broken.
- Abnormal and uneven wear.
Factors that cause the wheel to be unbalanced:
- Inherent quality uniformity(uneven density)
(1). Mixing, uneven molding compound
(2).The firing conditions are not uniform, and the shrinkage is inconsistent, and the reactions are inconsistent, causing the uneven density.
(3). When molding, there is geometric deviation, causing uneven pressure everywhere. After dressing the shape, although the geometric accuracy is achieved, the density is still uneven.
- Geometric accuracy ( shape and position deviation)
(1) Both ends are not parallel.
(2) The inner and outer diameters of the grinding wheel are decentration.
Therefore, in the actual use of the grinding wheel, Adjust the balance of grinding wheel is very important, the primary problem is to select the supplier of high quality grinding wheel to ensure the stability of the grinding wheel quality.